Screen



Jan. 2, 1934.

O. J. MILLS ET AL SCREEN 3 Sheets-Sheet 1 Filed June 6, 1932 INVENTO R OPE/c JJIY/LLS MLL/H/V 74 255 GORNEY Jan. 2, 1934. o. J. MILLS ET AL SCREEN 3 Sheets-Sheet 2 Filed June 6, 1932 Jain. 2, 1934. o. J. MILLS ET AL SCREEN 7 Filed June 6, 1932 3 Sheets-Sheet 3 -nmmw INVENTOR O/FP/ 117/443 MAL/9P7 6 M55 ATTORNEY Patented fan 2 1934 a nut or head 21 which is threaded on the screw flexible vibratory diaphragm 10 which may be composed of a sheet of rubber or of rubber and fabric, and according to the present invention, this diaphragm is inclined downwardly and laterally toward one side of the screen, its peripheral edge being secured to and forming a fluid-tight joint with a ledge 11 formed on the frame 2 and the transverse members 8. The diaphragm is provided with means for vibrating itin a direction transverse to its plane, such means, according to the present invention, comprising'a rocker lever 12 which is pivoted intermediately of its ends on a pivot pin 13, one end of this lever being bolted or otherwise secured to the lower end of a spring steel plate 14 and the upper end of the latter being bolted or otherwise fixed to a plate 15 beneath the diaphragm, the diaphragm being clamped between this plate and an upper plate 16. The spring steel plate 14 is bolted to the diaphragm plate 15 so that it extends perpendicularly tothe plane of the diaphragm, in consequence of which rocking movements of the lever 12 and which causereciprocations of the plate 14 will vibrate the diaphragm to equal extents at all points around its circumference.

The wall of each chamber 9 which is at the lowest edge of the diaphragm 10 is provided with an outlet passage 17 which leads from said chamber above the diaphragm, and this passage leads into a flow box 18 which extends longitudinally along that side of the screen and communicates with the similar outlet passages from the other chambers and serves to collect the screened pulp therefrom. Each outlet passage 17 is provided with a gate 19 which is preferably arranged at the outer end of said passage and is guided to move vertically, this gate serving to cover more or less or to fully uncover the passage 17 and thereby vary its effective area, or the gate 19 may be fully lowered to completely close said passage. Any. suitable means may be employed for adjusting the gates 19, they being preferably independently or individually adjustable, each gate being provided for this purpose in the present instance with a screw 20 which extends upwardly therefrom and and supported by the adjacent wall of the flow box so that rotation of the nut or head in the appropriate direction will raise or lower the respective gate and thereby vary the effective area of the corresponding outlet passage 1'7 or will completely open or completely close this passage, as occasion may require. The flowbox is divided longitudinally by a partition 22 abovewhich extends a dam 23 which is adjustable vertically in provided with screws 25 and cooperating nuts or heads 26 which are adjustable to raise and lower the dam as occasion may require. The dam divides the portion of the flow box into which the outlet passages 17 discharge from the compartment 2'7 thereof from which the screened stock discharges, the stock overflowing the upper edge of the dam to reach the discharge compartment 27. The screened stock may discharge from the compartment 2'7 of the flow box through an outlet .pipe 28 leading from the, bottom thereof. The stock to be screened is fed to one end of the screen;

vat bya chuteor other suitablemeans 29, the pulp stock suspended in water or other liquid flowing longitudinallyof the screen-,overthe screen plates and toward the opposite end of the screen.

The diaphragms are vibrated, during the operation of the screen, by the rocker levers 12 connected thereto in the manner above described, these rocker levers being actuated by a cam shaft 30. According to the present invention, the rocker levers 12 extend outwardly from beneath the respective diaphragms to points beyond a longitudinal side of the screen, and the cam shaft 30 is also mounted beyond a side of the screen so that the operating mechanism for the diaphragms will be readily accessible for inspection or repair and will be out of the path of any leakage of pulp from the screen which would impair the operative condition thereof. Preferably and as shown, the rocker levers and cam shaft are supported by a longitudinal girder 31 which is preferably composed of a one-piece casting or fabricated steel of rigid construction, it extending longitudinally at one side of the screen and being bolted or otherwise secured at its ends to the end members of the base 1. The inner side of the girder 31 is provided with an inward extension 32 for each rocker lever. 12, each of these extensions supporting a stationary pivot pin 13 on which the respective lever 12 is journalled. The cam shaft 30 is mounted in a suitable number of bearings 34 supported along the top of the girder, and the cam shaft has cams 35 fixed thereon, one vcam being provided for each diaphragm operating lever 12. The outer end of each lever 12 may be provided with an open top bearing 36 for a journal 37 of a pair of rollers 38, these rollers bearing against the underside of the respective cam 35. As an alternative, the outer end of each diaphragm actuating lever 12 may be formed with a socket 39 and clamping screw 40 to receive and holda toe block 41 composed of hard wood, fiber or other suitable wear-resisting material, this toe block bearing against the underside oftherespective cam. In either case, the bottom of the girder. 31 has an opening 42 extending upwardly. therethrough, this opening being surrounded by.

an upturned flange 43, and a coiled compression spring 44 extends upwardly through this opening and bears against the underside of the lever 46 which extends throughout its length, and the rollers 38 are partly immersedin the oil in this well and thus pick up oil therefrom tolubricate them and the cams. Inorderto-insure lubrication of the bearings of the levers 12 which engage the pivot pins 13, the top of each lever is provided with awell 47 which is adjacent to the rollers 38 so that it will receive oil picked up by these rollers, and an oil duct 48 leads from thewell- 4'? at an incline to an oil hole 49 in the hub of the lever 12 and which leadsto the bearing of the lever which engages the pivot'pin 13. The upturned flange 43'sur-rounding each opening 42 inthe bottom'of the; girder prevents leakage of the oil therethroughand the girder, which'is trough-shaped, provides an oil well throughout its length," for supplying oil to the operating means for all ofthe diaphragms' ofthe series.- The cam shaft 30 is driven continuously at an appropriate speed by a'belt pulley 130 fixed thereto or by any other suitable means. 9T0 enable .the screen plates to be easily and quickly cleaned when necessary, a pipe 50 is pro.- vided along one side of the screen vat, this pipe having. branches 51 which lead intothe reSpeC? tive chambers 9 through the sides thereof at the highest edges of the sloping diaphragms therein" and are provided withindividual controlling valves 52.' .The. pipe 59..is adapted to supply water, or any other suitable cleaning fluid, the individual valves provided enabling the water or cleaning fluid to be introduced. into any one or moreof the chambers, without. disturbing the screening operation in the remaining chamber orchambers; 1

' The operation of the screen, is as follows;

i. The pu1-p,,supended in water or liquid as usual, so that it; is fluid; is supplied to, one end of the screen'by the chute 29, it flowingonto the screen plates and travelling longitudinally toward the opposite end of the screen, and during the op, eration-ofthe soreen,;thecam shaft 30 is driven at a suitable speed, the cam 35 thereon rock.- ing. the series of rockfil' levers 1-2 and causingv them to'v rste therespectiv .d aphra ms 0 n a dir ct on pe p ndicular to the p ane there-.- ofr. The ates. 19 a e suitably adjus ed according to, the size of the slots or perforations in he s e pla es used and to t e. fineness r other h act sti sof the. pulp und rg screening, and the dam23 in the fiow box is adim ed to m nta n th i uid v l at the pr pe height in the chambers 9 with respect to the sc een; plates, h s, iquid level be n n mal y mmediate y be ow he. screen p at .T e vibratcrvm vem n o t e iaph aei s p e a ternate v a suc ionn -na tial vacu m i chambe -9 which act o f cib y draw th pu p dow war ly th o h e c ee lat s endto produces pr ssure n th chambe 9 wh h a ts o o e mostly air nd some liqui below t e re n pla es upw rdly through t e erforati ns here n .snch a terna su on and es ure asiot ne t e Pu p on t sc ee la es nd thus omotin and iasilita ins thescr snins ac The screen d ulp which pa ses ou h the screen plates into the chambers 9 ilovls outvr d y therei mh ushthe re ec ive out e a sages 7 into. the fl w box .18 and then over.- ws the u per ed e at the dam 23 the dis: ha e compa tment? whe ce i ma b c nducted teendes red fo further treati t t emalsins o P nsrcr for oth o rpose c o dmg to he. n ture o th ruin trea d," r

- y clinin or lopin ach diaph agm 1.0 etsral vand ov wanllyv ward e new box at'the side of the screen the accumulation of dirtor slime on theupper surface of the diahram a takes p a e a id o e u ual diaph agm c eens, i s bstant lvavoided nce the slope of the diaphragm toward the respeci veoiit n ss e and fl w b x insu he diaphragm also enables astln ht and direct outlet passage to be formed between each cham-.

ber. above the diaphragm and the flow box, ther.e.-.

byipermitting a more rapid and unimpeded flow of. the pulp from beneath .each screen and 'into thaflowbox; Furthermore, the-lateral slope or inclination of each diaphragm enables an out: let passage who used which is much larger than hasv heretofore been possible, it enabling an outlet passage to be .used for each vacuum and pressure chamber which has an area. equal to or greater than the agrgegate meant the slotsor perforationsin the respective pair of screen plates, so that the flow of the pulp through the screen plates will not be obstructe or impeded by the outletpassage. t'.

,'The lateral slope or inclination of the -.dia-v phragm in conjunction with the outlet pamage 17 of large area'and controlled as .to its-.efiec:

tive area by the gate, 19 enables increased efli:

enemy in theiscreening operation and increased capacity of the screen to be obtained since. the effective area of the discharge passage 1'7 may be adjusted 'bythe gatel9 to. regulate the degree of vacuum and pressure produced in the chains her 9 .by the diaphragm according to the size of the perforations inthe screen plates and the character of the stock being screened and to per: mit the outflow of the stock from the chamber 9 as rapidly as. the screening operation takes place, it being. understood that :when screen plates having relatively small perforations there: in are used or relatively long fibered stock is being screened, the gate 1 9. wil1 be lowered to reduce the effective areaofthe outlet passage 17. and thereby increase the degree of vacuum and pressure produced .in the chamber 9, and when screen plates having relatively large perforations;

therein are used or relativel-yshort fibered stock-is.

tions of the diaphragm and consequently -in,-.. r a in or redu the int nsity at whi h th 13 1 is forced-vertically through the screen plates, this result. being accomplished without. the n c ssity ofv ry e th thr o the c m. or other p rts of the iaphragm p ratin The provisiQh of the gates 19 with the vertically adjustable dam 23 in the 119W box e ables g ater efilcien v in th scre ning operation and increased capacity of thescreen to;

e obtained, sin e th sates lsenable the most fie ve vacuum and pressur acti n o tech a ned on the s reen ates and t e d rn .3. en:

ah esthe 'ulp to be mai tain d at thev most ef ect.

re leve en ath h creen la es, hil h -+1 mitting h s r ned Pu p. o t w octet the rs e eath the ree nla esas r n dl as the screening action permits. Sincethegates 19 area ius a e d p nd nt 0f the 31 2 nd, a sh w r l a ed be w hsl vsl Qtths to 9? said arn and he ce ar u mer ed n the pu p, the a he set or adjusted to obtain an desired intensity of vacuum and pressure be;

neath the screen plates, Without being limited by .v

the height ofthe liquid or pulp in as determined by the dam '23..

The lateral sloping of the. diaphragms and the. provision of the gates for regulatingthe degree Ofsuction-and pressure exerted on thescreen plates minimizes-the necessity of cleaning the diaphragms of accumulated dirt orslime or the screen plates due to clogging. The present invention, however, provides means for effectively cleaning the diaphragms and screen plates without the necessity of removing the screen'vat from the frame as heretofore required. Any one or more of the diaphragms and the respective screen plates maybe cleaned, according to the present invention, by fully lowering the respective gate or gates 19 andthereby completely closing the respective discharge passages 17, and opening upper sides of the respective diaphragms and to be carried upwardly through the screen plates by the flow of the water or washing fluid, this upflow of the water or washing fluid through the screen plates serving to unclog them, and this unclogging action is assisted by r the alternate vacuum and pressure or agitating action of the vibratory diaphragm. The matter thus dislodged by the washing fluid is carried on to other screen plates in the series which are performing their screening operation and is thereby rej. screened. By thus enabling one or more of the units of the screen to be washed while the remaining units thereof continue their screening operation, interruption of the operation of the entire screen is avoided, thereby saving much time and increasing the output of the screen.

The increased efficiency in the screening action obtained by regulating the degree of vacuum and pressure according to the size ofthe screen plates used and the character of the stock being screened and the regulation of the liquid or pulp level below the screen plates according to the rapidity of the screening operation increases the capacity of the screen or enables a screen to be used having a smaller number of screen plates to obtain a given capacity and also enables the cam shaft to be driven at a speed lower than that usually required in screens of this type, thus saving power in the operation of the screen.--

Bymounting the cam shaft above the'roller or toe blockend of-the rocker lever, the'opposite end of which is connected to the diaphragm for vibrating it and substantially balancing the weight of the diaphragm and the pulp above it by the cam shaft, a saving inthe power required to Vibrate the diaphragms is obtained, particularly since the cam shaft will be supported so that it substantially floats in its bearings.-

We claim as our invention: v

1. A screen comprising a vat containing a screen plate, a flow box extending longitudinally at one side of the vat, and a vibratory diaphragm closing the bottom of a chamber between it and the screen plate and sloping downwardly toward the flow box,such chamber-having an outlet passage extending laterally through the side thereof which is at the lowest edge of the diaphragm and formingdirect communication between said chamber and flow box.

,2. A pulp screen comprising a vat containing a screen plate, a flow box at a side thereof, a-

chamber beneath the screen plate having an out let passage in the side thereof adjacent to the flow box and communicating therewith, and a vibratory diaphragm closing the 'bottom'of said chamber and sloping laterally and downwardly toward the flow box and to a level below said outlet passage for the directdischargeof screened pulp from said chamber through said outlet into the flow box. v

1 3. A pulp screen comprising a vat for the-Iongitudinal flow of the pulp therein and containing a flat iscreen surface, 'aiflow box at a side of the vat, a chamber beneath the screen surface, and a vibratory diaphragm forming the bottom" of said chamber. and sloping downwardly toward the flow box, the side wall of said chamber at the the lowest edge of the diaphragm being adjacent to the flow box and said 'wall having an outlet passage extending. laterallyitherethrough at a level above saidlowest edge of the diaphragm and leading from"s'ai'd chamber to the 'fiowbox for the direct discharge of pulp from said chamber above the diaphragmto the flow box.

4 A pulp screen comprising a vat containing a screen surface, a chamber beneath said surface, a vibratory diaphragm operative to produce alternate pressure and vacuum conditions in said chamber, an outlet passage leading from said chamber, a dam to receive pulp from said outlet passage and control the level of pulp in said chamber, and a gate the lower edge of which is below the level of the top of the dam and is adjustable to different distances above the beta tom of said outlet passage to vary the effective area thereof. I

.'5. A pulp screen comprising avat containing a screen surface, a chamber beneath said su'r face, a vibratory diaphragm operative to produce alternate pressure and vacuum conditions in said chamber, a flow box, an outlet passage leading fromsaid chamber to the new box, the flow box having a dam the height of which is adjustable diaphragm, an outlet passage leading from the" side of said chamber atthe lowest edge of said diaphragm, means for closing said outlet passage, andmeans for introducing a washing fluid into the side of said chamber at the highest edge of said'diaphragm.

-7. In a screen comprising a vat containing a screen surface and a vibratory diaphrag m;beneath said surface, a rocker lever having amemf b'er connected to' one end thereof and attached to the diaphragm, and a cam shaft mounted above the other end of said rocker lever for actuating it and the diaphragm and for. substan tially balancing the Weight of the diaphragm? 8. In a screen comprising a vat containing a screen surface and a vibratory diaphragm beneath. it, a pivoted rocker lever connected atone end to the diaphragm for vibrating it, acam shaftmounted above and operative upon thefl other end of said lever for rocking it, oil reservoir containing the. pivoted andz-cam shaft.

operated portions of said lever for supplying oil thereto, the bottom of said reservoir having an opening therein and an upturned flange surrounding such opening, and a spring extending through said opening in the bottom of the reservoir and bearing on the underside of said rocker 10. In a screen comprising a vat containing a screen surface and a vibratory diaphragm beneath it, a pivoted rocker lever connected at one end to the diaphragm, a roller on the other end of said lever, a cam engaging the upper side of said roller to rock said lever and vibrate the diaphragm, and a reservoir to contain oil in which said roller is immersed, the upper side of the rocker lever having a well to receive oil lifted by said roller from the reservoir and having a duct leading to the pivot of the lever for conducting oil thereto from said Well.

ORRIE J. MILLS. WILLIAM G. WEBB. 

